Dragnet is an American television series, enacting the cases of a dedicated Los Angeles police Detective, Sergeant Joe Friday, and his partners. The series is a spin off from the radio play of the same name. Both shows take their names from the police term "dragnet", meaning a system of coordinated measures for apprehending criminals or suspects. The ominous, four-note introduction to the brass and tympani theme music (titled "Danger Ahead") is instantly recognizable (though its origins date to Miklós Rózsa's score for the 1946 film version of The Killers). After its success on radio Dragnet was popular enough to move to Television. More important was that it brought continuity between the television and radio series.
Just before the show took its final commercial break, the show's announcer would inform the audience of something related to the case, usually the opening date on which the perpetrator's trial would take place in the Los Angeles County Superior Court (this would be accompanied by an onscreen card so the viewer could read along). After the break the camera faded in for what was presumably the perpetrator's mug shot, consisting of him/her standing uncomfortably against the wall, while the results of the trial were announced. The perpetrator's name and fate were then superimposed over the screen, specifically regarding what prison he/she was incarcerated in (or, in the case of perpetrators deemed unfit to stand trial, what state facility he/she was committed to)